The Free On-line Dictionary of Computing (30 December 2018):

tcl-debug

   A debugger for Tcl by Don Libes  that
   can be easily embedded in other applications.  It is included
   with many other Tcl libraries.

   (ftp://ftp.cme.nist.gov/pub/expect/tcl-debug.tar.Z).

   (1994-10-31)